Synthesis and Phase Stability of Scandia, Gadolinia and Ytterbia Co-Doped Zirconia for Thermal Barrier Coating Application

This study investigates a new zirconia-based ceramic for potential use in thermal barrier coatings. In the experiments, Sc₂O₃-Gd₂O₃-Yb₂O₃-ZrO₂ (SGYZ) powder was synthesized by coprecipitation and calcination, then agglomerated and sintered to facilitate spraying. The structure, morphology, and phase stability of the powder and plasma-sprayed SGYZ coatings were analyzed and thermal conductivity was measured. Test results show that the powders and coatings have good phase stability even after 500 h at 1400 °C and do not undergo tetragonal-to-monoclinic phase transition upon cooling. Plasma-sprayed SGYZ also has a lower thermal conductivity than YSZ, which is currently used in gas turbine engines.